The present invention generally pertains an injection-molded tie that is useful for forming a loop for retaining a bundle of elongated articles, such as cables, and is particularly directed to removal of the tie from the mold. Such a tie is commonly known as a cable tie.
One type of tie includes an elongated tongue with two ends and two broad sides, a locking head at one end of the tongue, a first set of ratchet teeth extending along one broad side of the tongue and a second set of ratchet teeth extending along the other broad side of the tongue, wherein the locking head has sides defining an opening for receiving the tongue, the sides include a movable pawl that is hinged at one side of said opening and an abutment surface that is across the opening from the pawl, and the pawl has at least one pawl tooth disposed for engaging the set of first ratchet teeth when the tongue has been inserted through said opening with the first set of ratchet teeth facing the pawl, wherein the pawl, when the at least one pawl tooth is so engaged, is movable toward the abutment surface in response to pressure applied to the tongue in a direction opposite to the direction of said insertion in order to force the second set of ratchet teeth against the abutment surface; and wherein the abutment surface includes at least one tooth, each having a facing surface extending toward an apex and a locking surface extending toward the apex, for locking engagement with the second set of ratchet teeth when the tongue has been inserted through the opening with the second set of ratchet teeth facing the abutment surface and the side of the tongue including the second set of ratchet teeth is forced against the abutment surface by movement of the pawl. This particular design of a tie is preferred because the combined engagement of ratchet teeth on both sides of the tongue enhances the retaining function of the tie. Such a tie is described in U.S. Pat. No. 4,473,524 to Paradis and U.S. Pat. No. 5,146,654 to Caveney et al.
A method of injection molding such a tie includes the steps of:
(a) providing a mold that includes mold parts joined at a parting line for defining a cavity between the mold parts in the general shape of the tie; PA1 (b) injecting molten plastic material into the mold cavity; PA1 (c) solidifying the plastic material in the mold cavity to form the tie; PA1 (d) separating the mold parts in a direction normal to the parting line to enable ejection of the tie from mold; and PA1 (e) ejecting the solidified tie from the mold. PA1 (a) providing a mold that includes mold parts joined at a parting line for defining a cavity between the mold parts in the general shape of the tie; PA1 (b) injecting molten plastic material into the mold cavity; PA1 (c) solidifying the plastic material in the mold cavity to form the tie, with the tie having an artifact line formed at the parting line while the plastic material solidifies in the mold cavity; and PA1 (d) separating the mold parts in a direction normal to the parting line to enable ejection of the tie from mold; and PA1 (e) ejecting the solidified tie from the mold; PA1 wherein step (a) comprises providing a said mold which defines a tie in which the direction of said insertion is at an obtuse angle to an extension of the artifact line from the abutment surface toward the pawl.
It would appear that unless (a) there is only one tooth on the abutment surface of the tie, and (b) the mold parts are separated at the portion of the mold cavity that defines the apex of the abutment surface tooth, the abutment surface tooth would be significantly damaged upon separation of the mold parts.